This invention relates to an antibacterial oral composition which promotes oral hygiene and in particular is directed to such oral composition which comprises a cationic nitrogen-containing antibacterial agent incorporated therein to prevent plaque formation caused by bacteria in the oral cavity.
As is described in more detail herein, such compositions have employed a wide range of antibacterial compounds such as quaternary ammonium compounds and substituted guanidines. Many of these compounds have been shown to effectively promote oral hygiene and, in particular, inhibit plaque formation. Unfortunately, however, it has been observed that the use of such oral compositions has led to the staining or discoloration of dental surfaces.
The reason for the formation of such dental stain has not been clearly established. It is believed however that stain results from the entrapment of stain chromophores in dental calculus. Cationic antimicrobials enhance the staining process by accelerating both the formation of the stain chromophores and the deposition of calculus. This phenonomon is described in A. Gaffar, et al., Journal of Dental Research, Vol. 60, No. 8, pp. 1432-1439 (August 1981).
The art has long sought to employ additives which reduce the dental staining properties of antibacterial agents. Thus, for example, in U.S. Pat. No. 3,934,002 to Haefele the staining properties of bis-biguanide compounds are sought to be inhibited by the inclusion of such compounds as zinc phenol sulfonates hydroxy quinoline, homopolymers and copolymers of aliphatic polycarboxylic acids, certain polyphosphates, certain salts of rare earth metals, phytic acid and certain polyphosphonates and ammonium polyphosphonates. In U.S. Pat. No. 4,042,679 to Gaffar the staining properties of bis-biguanido hexanes and quaternary ammonium salts such as benzethonium chloride and cetyl pyridinium chloride are said to be inhibited by employing as an antistain additive, a polymeric polyphosphonic compound such as polyalkyl bis-(phosphonomethylene) amine acid. In U.S. Pat. No. 4,224,309 to Gaffar, et. al., the antistaining properties of such bis-biguanido hexanes and quaternary ammonium salts are said to be inhibited by employing as an antistain additive a 2-phosphono-butane-1,2,4-tricarboxylic acid compound. In U.S. Pat. No. 4,118,474 to Gaffar, et al, the antistaining properties of such antibacterial agents are said to be inhibited by employing as an antistain additive phosphonoacetic acid and its salts.
For one reason or another, these prior suggestions have not proven to be widely used. For example, previously employed additives which reduced dental staining by cationic antibacterial antiplaque agents also generally reduced their antibacterial and antiplaque activities as by forming a precipitate with such agents.
Accordingly, it is desirable to employ, together with a cationic antibacterial agent, an antistaining additive which does not decrease the antibacterial, antiplaque activity of the antibacterial agent and thus far, a completely satisfactory additive has eluded the art.